Synthesis Of Rod-shaped Indium Oxide Composite Materials And Its Gas Sensing Studies

Volatile organic pollutants（VOCs）are causing increasingly serious harm to the air environment.Indium oxide（In₂O₃）has become a hot research topic for sensing materials due to its excellent gas-sensitive sensing performance and outstanding stability.In this work,two p-n heterojunction composites were prepared,and the surface modification of the main material rod-shaped indium oxide prepared by different methods with the same p-type semiconductor Co₃O₄ material was used to explain the differences of different p-n heterojunctions to enhance the gas-sensitive performance by combining morphology,electrical properties,and pore structure.The specific research content is as follows:The one-step hydrothermal method generates rod-shaped indium oxide with uniform particle size,and ZIF-67 modification is co-calcined on its surface to produce p-n heterojunction composites.Gas-sensitive testing revealed that the optimum composite ratio was Co:In 6 mmol%,and the composite H-In Co-6 reached a response value of 8550±450 to 100 ppm ethanol at 260°C,while the response value of pure material indium oxide at300°C was only 210.Combined the research findings with the material morphology,surface element state,electrical and optical properties.it was found that surface modification ZIF-67/Co₃O₄ could reduce the band gap,increase specific surface area,chemisorbed oxygen and Oxygen vacancy of material.the resistance ratio in two atmospheres was changed by the design of the p-n heterojunction structure,The composite has a great gas-sensitive response to ethanol gas.Indium oxide prepared by the template method of sacrificial MOFs,with uniform particle size,becomes a hollow rod-like structure after calcination,and is compounded with the same p-type semiconductor Co₃O₄mentioned above to construct a p-n heterojunction structure,and the best compound ratio of this composite is the same 6 mmol%,and the composite M-In Co-6 reaches 1950±48 at 280°C in response to 100 ppm ethanol gas,while the pure material indium oxide is 45 at 300°C.it was found that surface modification ZIF-67/Co₃O₄ could make the material larger specific surface area,lower band gap width and more surface defects,The construction of composites with different p-n type heterojunctions can increase the active sites on the material surface or accelerate the electron transfer from n-type to p-type semiconductors to generate electron-withdrawal layers,which becomes an effective mechanism to improve the gas-sensitive performance.